RAMADI, Iraq (AP) — Thousands of Iraqi demonstrators massed in a Sunni-dominated province west of Baghdad Wednesday, determined to keep up the pressure on a Shiite-led government that many accuse of trying to marginalize them.

It was the third major protest in less than a week in Anbar, Iraq's largest province, once the heart of the deadly Sunni insurgency that erupted after the U.S.-led invasion in 2003.

The unrest is part of a larger picture of sectarian conflicts that threaten the stability of the country, a year after the last U.S. troops left.

The demonstrations follow the arrest last week of 10 bodyguards assigned to Finance Minister Rafia al-Issawi, who comes from Anbar and is one of the central government's most senior Sunni officials. The case is exacerbating tensions with Iraq's Sunnis, who see the detentions as politically motivated.

Protesters turned out Wednesday near the provincial capital Ramadi, 115 kilometers (70 miles) west of Baghdad. The city and nearby Fallujah were the scenes of some of the deadliest fighting between U.S. troops and Iraqi insurgents.

Demonstrators gathered along a highway linking Baghdad with neighboring Jordan and Syria. They held banners demanding that Sunni rights be respected and calling for the release of Sunni prisoners in Iraqi jails. "We warn the government not to draw the country into sectarian conflict," read one. Another declared: "We are not a minority."

Al-Issawi made an appearance at the rally, arriving in a long convoy of black SUVs protected by heavily armed bodyguards. He condemned last week's raid on his office and rattled off a list of grievances aimed at Prime Minister Nouri al-Maliki's government.

"Injustice, marginalization, discrimination and double standards, as well as the politicization of the judiciary system and a lack of respect for partnership, law and constitution ... have all turned our neighborhoods in Baghdad into huge prisons surrounded by concrete blocks," he declared.

Iraq's majority Shiites rose to power following the 2003 U.S.-led invasion that ousted Saddam Hussein's Sunni-dominated regime, though the country's minority Sunni Arabs and Kurds do hold some posts in the government.

Many Sunnis see the arrest of the finance minister's guards as the latest in a series of moves by the Shiite prime minister against their sect and other perceived political opponents. Vice President Tariq al-Hashemi, one of the country's highest-ranking Sunni politicians, is now living in exile in Turkey after being handed multiple death sentences for allegedly running death squads — a charge he dismisses as politically motivated.

"This sit-in will remain open-ended until the demonstrators' demands are met, and until the injustice against ends," cleric Hamid al-Issawi told The Associated Press at the protest. He accused al-Maliki's government of trying to create rifts between Sunnis and Shiites.

"These practices are aimed at drawing the country into a sectarian conflict again by creating crisis and targeting prominent national figures," the cleric said.

Al-Maliki has defended the arrests of the finance minister's guards as legal and based on warrants issued by judicial authorities. He also recently warned against a return to sectarian strife in criticizing the responses of prominent Sunni officials to the detentions.

In a recent statement, the prime minister dismissed the rhetoric as political posturing ahead of provincial elections scheduled for April and warned his opponents not to forget the dark days of sectarian fighting "when we used to collect bodies and chopped heads from the streets."

The political tensions are rising at a sensitive time. Iraq's ailing President Jalal Talabani is incapacitated following a serious stroke last week and is being treated in a German hospital. The 79-year-old president, an ethnic Kurd, is widely seen as a unifying figure with the clout to mediate among the country's ethnic and sectarian groups.

Also Wednesday, the United Nations mission to Iraq said its monitors have determined that a hospital that treated a member of an Iranian exile group who died this week at a refugee camp near Baghdad did not consider his health condition serious enough to warrant hospitalization when he arrived for treatment in November.

An organization representing the Mujahedeen-e-Khalq exile group on Monday accused Iraqi authorities of preventing 56-year-old Behrooz Rahimian from being hospitalized, and alleged that the U.N. failed to take sufficient steps to intervene. Iraq considers the MEK a terrorist group and wants its members out of the country.

The U.N. mission in Baghdad said in a statement Wednesday that it "does not have any indication so far that treatment was obstructed by the Iraqi authorities." It noted that representatives for the refugee residents told U.N. monitors that Rahimian "appeared to be in good condition until the time of his death."